Preheat your oven to 350 degrees Fahrenheit, and line a square baking dish with parchment.
In a large mixing bowl, whisk together the melted butter and sugars.
Add the eggs and vanilla, and whisk to combine.
In another bowl, whisk together the flour, baking powder, and salt.
Slowly add the flour mixture, whisking, and then folding with a spatula once the dough begins to thicken.
Continue until all flour is added, careful not to over mix.
Fold in the M&M candies.
Spread the dough into the parchment lined baking sheet, and bake 35-40 minutes. The blondies will be puffy and golden brown.